1. Field Of The Invention
This invention relates to smoking articles preferably in a cigarette form. In one aspect, it relates to a smoking article which produces an aerosol that resembles tobacco smoke but has substantially reduced amounts of smoke as produced by conventional cigarettes. In another aspect, the invention relates to a smoking article wherein tobacco is utilized as a flavor generating system. In even another aspect, the invention relates to a smoking article wherein tobacco flavors therein are volatilized but the tobacco is not combusted.
2. Description Of The Prior Art
Many smoking articles have been proposed in the last few years wherein tobacco or other carbon fuel sources are utilized to heat a core of tobacco or tobacco substitutes to a temperature less than the combustion temperature for the tobacco or tobacco substitutes, but which will volatilize the tobacco flavors contained within the core products.
These proposed smoking articles have been in many instances based on the use of heat to generate an aerosol or vapor containing tobacco flavors. Moreover, many different smoking articles have been proposed which actually burn a fuel source, which may be tobacco or other carbon sources, as a heating fuel wherein the heat generated from the combustible elements volatilize the tobacco flavors either from tobacco or a tobacco substitute material. The earliest such smoking articles were described in U.S. Pat. No. 3,258,015 to Ellis et al which teaches the use of a high heat tubular member containing a nicotine-releasing material surrounded by any heating means which will heat the nicotine-releasing material to a temperature between 200.degree. and 400.degree. C. The nicotine-releasing material may be tobacco, reconstituted tobacco, tobacco extract, or a synthetic mixture containing nicotine, such that nicotine is from 5% to 20% of the material by weight. This reference further teaches the use of fine cut tobacco for the heating means and mixing it with smoldering enhancers such as sodium chlorate, potassium chlorate, sodium nitrate, or potassium nitrate. Moreover, other materials such as carbon fuel may be used as the heating means. The Ellis et al patent further teaches the use of an aerosol-nucleating chamber which allows cooling so that the nicotine vapors condense on the aerosol particles. This chamber may be between the mouthpiece or filter and the heating means, in the middle of the tubular member, or some combination of these.
In U.S. Pat. No. 3,356,094 to Ellis et al, the metal tubular member of the '015 Ellis et al patent is replaced with a frangible or friable material. This reference teaches using an inorganic salt which loses water or carbon dioxide and becomes brittle when heated. Salts disclosed are magnesium sulfate heptahydrate, magnesium carbonate trihydrate, basic carbonates of magnesium, sodium or potassium bicarbonate and calcium sulfate. Plasticizers listed are colloidal silicate, magnesium oxide, ground chalk, and kaolin. Another reference, U.S. Pat. No. 4,474,194 to Steiner, teaches the use of ceramics or baked clays to separate the heating means from the tobacco simulating substance. Moreover, this reference teaches replacing tobacco as a heating means with a cellulose-base product mixed with activated charcoal and impregnated with appropriate aromatic compounds to provide a tobacco-like aroma.
U.S. Pat. No. 4,714,082 to Banerjee et al teaches placing the heating means and the aerosol-generating means in a tandem relationship rather than a coaxial relationship as set forth in the previously discussed references. In Banerjee et al, the heating means may contain combustible carbon in addition to reconstituted carbon and the aerosol generation means may contain alumina impregnated with an aerosol-forming material with a mass of tobacco located adjacent thereto.